Gate operating mechanism for a concrete bucket



Nov. 12, 1957 E. o. MARTINSON GATE OPERATING MECHANISM FOR A CONCRETE BUCKET 4 Shuts-Sheet 1 Filed Feb. 26, 1949 "van-raw Edwin nkqv-ti n iygvg W x p I mmv" Nov.-12, 1957 E. o. MARTINSON 2,812,970

GATE OPERATING MECHANISM FOR A CONCRETE BUCKET Filed Feb; 26, 1949 I 4 Sheets-Sheet 2 Nov. 12, 1957 E. o. MARTINSON GATE- OPERATING MECHANISM FOR ACONC'RETE BUCKET Filed Feb. 26; 1949 4 Sheets-Sheet 3 IQS Nov. 12, 1957 E. O. MARTINSON GATE OPERATING MECHANISM FOR A CONCRETE BUCKET Filed Feb. 26. 1949 4 Sheets-Sheet 4 Nvnro'fc BdwL n s 60 (BTTOIIN :Y/

United States Patent GATE OPERATING MECHANISM FOR A CONCRETE BUCKET Edwin O. Martinson, Milwaukee, Wis., assignor to The C. S. Johnson Company, Champaign, Ill., a corporation of Illinois Application February 26, 1949, Serial No. 78,481

22 Claims. (Cl. 294-71) The present invention relates to concrete buckets and more particularly to buckets of the bottom dump type.

It is an object of the present invention to provide an improved concrete bucket having double clam discharge gates for operation by compressed air in which the opening is effected with sufiicient force to insure positive movement even with a full load of concrete and in which the gates are closed almost instantly either by manual valve operation or automatically upon disconnecting the air supply line.

It is a further object related to the above to provide an improved pneumatic system for controlling a double clam discharge gate which is fail-safe, which does not require the exercise of particular skill or effort by the operator, and which enables the operator to stand clear of the bucket at the time of opening.

It is still another object of the invention to provide an improved concrete bucket in which the gates are forcefully held closed while the bucket is being transported and in which the holding pressure is released and the opening force applied by means of an air line inserted into the bucket at the point of pouring. It is an allied object to provide a power-operated bucket including provision for simple and easy manual operation of the gates where compressed air is not readily available.

Other objects and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings, in which:

Figure 1 is a general external view of a bucket constructed in accordance with the invention.

Fig. 2 is a side elevation of the improved bucket with certain parts broken away to show the shape of the container portion.

Fig. 3 is a fragmentary elevation showing the linkage employed to operate the gates and with the gates in the closed position.

Fig. 4 is a side view taken at right angles to the view of Fig. 3.

Fig. 5 is a fragmentary view similar to Fig. 3 but with the gates in the fully opened position.

Fig. 6 shows the pneumatic system used in combination with the linkage of Figs. 3 and 5.

Fig. 7 is an enlarged view of the receiver in the system of Fig. 6.

Fig. 7A is a fragmentary detailed view of an inlet used in the system of Fig. 6.

Fig. 8 is a plan view which, taken together with Fig. 2, shows the pneumatic system installed in the bucket.

Fig. 9 shows an operator inserting the air lance prior to compressed air operation of the gates.

While the invention is susceptible of various modifications and alternative constructions and uses, I have shown in the drawings and will herein describe in detail one embodiment of the invention. It is to be understood, however, that I do not intend to limit the invention by such disclosure, but aim to cover all modifications and alternative constructions and uses falling within the 2,812,970 Patented Nov. 12, 1957 spirit and scope of the invention as expressed in the appended claims.

Referring now to Figures 1 and 2 it will be seen that the bucket has a container 2.0 which includes an upper cylindrical portion 21, a funnel portion 22, and a throat portion 23 of large diameter all smoothly welded together. The angle of the funnel portion is very steep in order to produce rapid and positive discharge, making an angle on the order of 22 degrees with the bucket axis. To support the container and protect the working parts, legs 24 are provided. These are formed of wide channels merging smoothly at their upper ends with the circular portion 21 and Welded at their lower ends to a ring 25 of corresponding diameter.

The throat 23 of the bucket is closed by a pair of clam type discharge gates 30, 31 which are operated by a piston and linkage assembly 32, one such assembly being located on each side of the bucket. This assembly includes a bail-shaped operating handle 33 which partially encircles the bucket and normally occupies the position 34. This bail swings downwardly when the bucket is operated by compressed air and may be pulled downwardly by the operator as shown when compressed air is not available.

The bucket further includes a lifting bail 40 for gripping by a crane hook or the like.

In Fig. 2 the gates 30, 31 are shown fully retracted to permit concrete to How readily from the upper portion of the bucket through the throat. This is facilitated by the steep angle previously referred to and by using a throat on the order of 42 inches in diameter permitting the type of concrete flow known in the art as folding action. It will be noted that the two halves of the throat are scalloped so as to mate with the arcuate gate plates and the edges thereof include a rubber gasket 45 to further seal against leakage. The gasket is preferably mounted for adjustment to take care of any wear which may occur over long periods of use, this matter of adjustment being well within the capability of one skilled in the art.

In order to understand the construction of the linkage assembly 32 and the manner in which the buckets 30, 31 operate for discharge, attention is next directed to Fig. 3. Thrust to operate the gates 30, 31 is obtained from a ram having a cylinder 51 which is pivotally anchored to I the bucket frame at its upper end at a point 52 and which includes an operating plunger 53 shown in the retracted position. At its lower end 54 the plunger is pivotally connected to an operating arm 55. The latter is made up of two vertically arranged and parallel strips of metal as indicated in Fig. 4 and has a laterally offset portion 56 at its lower end for pivoting the same about a fixed pin or spindle 57. At its outer end the spindle S7 is supported by a bracket 58 while at its inner end it is received in a hanger bracket 60 which includes a mounting flange 61 and a depending skirt 62.

Centrally pivoted on the spindle 57 and rigidly fixed for rocking movement with the vertical arm 55 is a rocker 70 which includes a pair of laterally spaced metal plates having pivot connections 71, 72 at the respective ends thereof. Sandwiched between the plates and pivoted at 71 is a first thrust link 73 connected to the gate 30 at a point of pivoting 74. Lying directly above is a second thrust link which is connected at one end to the pivot 72 and which extends to the left for pivoting engagement with the second gate 31 at a point 81.

Prior to discussing the function and arrangement of the thrust links 73, 80 it will be helpful to inspect the construction of the gates in greater detail. The gate 30 for example includes sector-shaped end pieces which are similarly shaped and welded along their lower edges to an arcuately-shaped gate plate 91. An angle bar 92 is welded to the gate plate and extends therealong for purposes of reinforcement. The gate is pivoted pendulum-like on a pivot pin 93. The latter is mounted in the some hanger bracket used to support the arm 55 and rocker previously referred to. Friction at the pivot 93 is minimized by the use of self-alining roller bearings 94. To receive the outer end of the thrust link 73, the end plate of the gate has welded thereto a bracket 95 which includes a pair of spaced plates having a pocket in line with the thrust link 73.

Turning attention now to the remaining gate 31 it will be found to be of substantially the same construction as the gate 30. It includes a pair of sector-shaped end plates and an arcuately curved gate plate 101 welded thereto having a reinforcing angle 102 extending along the length thereof. This gate is likewise suspended from the hanger bracket 60, in this case by means of a pin 103, having an anti-friction bearing 104. A bracket 105 Welded to the end plate 100 has a pocket therein which receives the thrust link 80 for pivoting at 31.

In order to provide a more perfect seal for the fluid constituents of the concrete, and to better retain grout without leakage, the gate plates 91, 101 have a center of curvature which lies a short distance inwardly of the gate pivot pins 93, 103. Such centers of curvature are indicated at 96, 106 respectively. The gasket 45 (Fig. 5) at the lower edge of the throat 23 has an arcuate contour which closely mates with the contour of the gate plates 91, 101 when the latter are in their fully closed position. As will be apparent to one skilled in the art offsetting the centers of curvature of the plates 91, 101 as indicated has the effect of applying a radially inward force component on the gasket 45 (Fig. 5) when the gates are fully closed and in the position shown.

This sealing force is relieved during the first portion of the outward or opening movement of the gates. To further insure against leakage the plates 91, 101 are caused to overlap slightly at their mating edges by bend ing the lip of one of the plates downward slightly as indicated at 107.

In accordance with one of the aspects of the invention each of the thrust links 73, 80 is so arranged with respect to the rocker 70 that the mechanical advantage is initially a maximum and is gradually reduced as the associated gate is swung from the closed position to the fully opened position. This, in the present arrangement, has been accomplished by arranging the rocker 70, the link 73 and the link 80 all in general parallelism with one another with the gate closed. Thus the link 73 extends from side to side below the rocker pivot 57 while the link 80, lying generally above, arches over the rocker pivot. Both links are preferably curved to enable clearance while obtaining maximum initial leverage. The variation in the mechanical advantage will readily be seen by comparing the effective lever arm of the rocker 70 acting on the left-hand end of the thrust link 73 in the closed and open positions respectively.

It will be noted in Fig. 3 that the effective lever arm at the left-hand end of the thrust link 73 is extremely small. The latter, as indicated at 110, is the perpendicular distance between the pivot 57 and the chord 111 which connects the pivots at the ends of the thrust link. Upon counterclockwise rotation of the rocker 70 as viewed in Fig. 3 the thrust link 73 will be bodily moved to the right, exerting pressure at the pivot 74 and tending to swing the gate 30 outwardly. Such movement is accompanied by a lowering of the thrust link away from the pivot 57 causing the effective lever arm to increase until it reaches a value indicated at 112 (see Fig. 5) which is approximately six times as great as it was originally.

Further in accordance with the invention the point of connection of the thrust link 73 to the gate relative to the point of pivoting of the gate is so arranged that the mechanical advantage in opening the gate varies from a maximum to a minimum. This will be readily seen by comparing the effective lever arm between the thrust link 73 and the point of pivoting 93 of the gate. The effective lever arm is here indicated at 113, being the perpendicular distance between the chord 111 and the pivot 93. With the effective lever arm 113 of the length shown in Fig. 3 it will have maximum leverage in forcing the gate 30 outwardly, but upon progressive movement of the gate the lever arm will be progressively reduced until it is of the length indicated at 114 in Fig. 5. This length is approximately 0.57 times the initial length. As a result of the foregoing relationships the overall variation in mechanical advantage between the closed position shown in Fig. 3 and the open position of Fig. 5 is seen to be in the ratio of 10 to l.

The foregoing relationships need not be gone into in detail in the case of gate 31 but substantially the same ratios exist. Drawing attention to the thrust link 80 connected thereto, the initial lever arm is of a length indicated at being the perpendicular distance from the pivot 57 to the chord 121 connecting the points of pivoting 72, 81. This effective lever arm is increased to the value indicated at 122 in Fig. 5 when the gate 31 is open. At the other end of the thrust arm 80 the effective lever arm begins at a relatively large value 123 being reduced to the length 124 when the gate 31 is swung to its outer most position. Although the link 80 is somewhat shorter than the link 73 it will be noted that the effective lever arms are such as to produce substantially the same overall range of mechanical advantage.

When the gates 30, 31 are in their closed position they are suspended in the manner of a pendulum and consequently the weight of the gates themselves will have no tendency to cause movement in opening or closing directions. As a result the full force of the plunger 53 will be available to open the gates even though the latter may be loaded with many tons of concrete having aggregate up to six inches or more in size. When the bucket has been transported a considerable distance and when the concrete has remained in the bucket for some time there will be a tendency for premature packing to take place which makes the concerete stiff and unyielding and greatly increases the difficulty of opening the gates. Tests with the bucket disclosed herein indicate clearly that the large initial mechanical advantage greatly facilitates opening the gates using only a moderate thrust from the ram even with a maximum load.

While it has been assumed in the above description that the ram 50 has been utilized to cause opening of the gates. it will be appreciated upon inspection of Fig. 3 that the same variation in mechanical advantage is available where operation is entirely manual. Thus in Fig. 3 the bail 33 is shown connected to the upper end of the operating arm by means of bolts 125. it will be seen that pulling downwardly on the bail 33 causes clockwise rotation of the rocker 70. Normally this may be accomplished by one man where air is not available, with the man standing in a safe position clear of the bucket. Under transport conditions the bail 33 occupies an out-of-the-way position 34 encompassing the conical portion 22 of the bucket. The bolts 125 may be readily unscrewed for removing the bail when compressed air is available at all of the pouring locations.

To simplify understanding only one of the linkage assem-blies 32 has been discussed. It will be understood. however, that an identical assembly is provided at the op posite ends of the gates and arranged for actuation by an identical air ram so that the force available is twice as great as that which would be available from a single linkage assembly and is evenly applied to the gates. This completely eliminates any tendency for the gate to distort or for misalinement of the supporting bearings to take place as a result of operating pressures.

In accordance with another aspect of the invention the bucket includes a novel pneumatic system which comprises a reservoir of compressed air and an arrangement of valves such that application of compressed air causes forceful opening of the gates while opening of the line causes forceful and positive closing of the gates. Such opening of the line may be either effected by a manuallyoperated valve or by bodily removing the nozzle of the air supply line. The operation will be made clear by inspection of Fig. 6 which is a schematic layout of the system together with Figs. 2 and 8 which show the air lines and associated elements mounted within the bucket structure.

In Fig. 6 the pneumatic system includes the ram 50 previously discussed and a similar ram 500: located on the opposite side of the bucket. These rams which are double acting include cylinders 51, 51a and plungers 53, 53a. Air pressure to move the plungers in the gate opening direction is supplied through pressure lines 131, 131a while pressure may be applied to cause movement in the reverse or closing direction by means of the lines 132, 132a. Control of the compressed air supply lines is achieved in the present instance by means of an air-operated slide valve 133, an air receiver 134, and air inlet devices 135, 136 respectively. The -latter may be alternately engaged by an insertable air lance 140 supplied from a portable air line 141 to a manually-operated valve 142. In the practice of the invention the air receiver 134 and the slide valve 133 are eflective to cause compressed air from a self-contained source to flow into the rams to cause closing movement thereof whenever the air supply at the inlet devices 135, 136 is reduced to atmospheric. To understand how this is accomplished the construction of the air receiver 134 and the valve 133 will be considered in greater detail. Turning first to the valve it will be seen that it includes a valve plunger 150 movable between an upper position in which compressed air is supplied to the lines 131, 131:: and a lower position in which air is supplied to the lines 132, 132a. Air for this purpose flows to the valve via a supply line 151. Connected to the plunger 150 is a control piston 152 which is biased in a downward direction by means of a spring 153. Pressure is applied below the piston 152 from a valve control line 154. With the valve mechanism in the position shown, the spring 153 is in its compressed condition indicating the presence of compressed air in the control line 154.

As shown in Figs. 2, 6 and 7 the air receiver 134 has a base portion 160 to which the various air conduits are connected and a reservoir portion 161. Extending transversely within the receiver base is a channel or bore 162. This channel is supplied with compressed air either from the air inlet 136 via a line 163, or alternatively, from the inlet device 135 via a line 164. The valve control line 154 is connected to the mid-point of the channel 162 by means of a transverse channel 165. It will be apparent, then, that application of compressed air from an outside source will always have the effect of causing the slide valve 133 to assume the condition shown.

In order that air supplied to one of the inlet devices might be prevented from leaking out of the other, a ball check valve 170 is provided which has seats 171, 172 lying at either end of the channel 162. As a result air supplied to the inlet device 135 will tend to drive the ball 170 into the upper position shown after which the air will be sealed against escape and will flow to the rams.

Drawing attention to the right-hand portion of the receiver shown in Fig. 7 it will be noted that there is a second ball check valve 175 conecting the transverse channel 165 to an outlet channel 166 leading to the valve supply line 151. This valve is kept in the closed position in the absence of external pressure by means of a spring 176. The outlet channel 166 also has a connection with the reservoir 161 via a downwardly extending opening 178. As a result of the above, admission of compressed air to either of the inlet devices 135, 136 will cause compressed air to be admitted simultaneously to the control line 154 of the valve, to the right-hand portion of each of the rams 50, 50a, and the the reservoir 161. This results in an immediate outward thrust of the plungers 53, 53a which, acting through the linkage assembly 32 on each side of the bucket, produces a powerful opening force on the gates 30, 31.

Upon removal of air pressure from the air inlet the gates will be quickly and positively closed in accordance with the following sequence. There will be two initial effects. The spring 153, relieved of pressure, will expand thereby causing the control piston to move from its upper to its lower position. Simultaneously, the spring 176 will expand causing the ball valve associated therewith to close, sealing off the reservoir from the pressure inlet. Consequently air under pressure will flow from the reservoir through the valve supply line 151 and thence through the ram supply lines 132, 132a. This causes immediate retracting movement of the ram plunger-s 53, 53a and forceful closure of the gates.

While it is true that the mechanical advantage at the beginning of the closing stroke is not as great as at the beginning of the opening stroke, nevertheless it has been found that complete closure occurs in one second or less in the various practical designs which have been tested. There are a number of reasons for this. In the first place there is little concrete in contact with the gates as they begin to close, consequently the frictional drag is at a minimum. Initial closure is facilitated by the fact that the gates are pendulously upraised and are therefore subject to the action of gravity. Another factor assisting closure is that the path of movement of the gate plates 91, 101 is practically at right angles to the weight and direction of movement of the concrete.

The means used to apply compresed air to the bucket at the point of pouring was alluded to only briefly above and it will be helpful to describe the construction of the inlet devices 135, 136 in greater detail. Such construction is set forth in the fragmentary section shown in Fig. 7A. Taking the air inlet 135 for example, it will be note-d that provision is made for sealing against the escape of air while permitting considerable angular movement of the lance or nozzle 140 about the point of entry. To this end a conical rubber diaphragm 180 is used having an aperture 181, surrounded by a flexible lip 182. In addition, the socket 183 adjacent the diaphragm has a conical guide surface 184. This permits easy insertion of the lance even when it is in the angular position indicated at 185. In addition to enabling angling of the lance, the flaring surface 184 provides a month which is sufficiently large in diameter so that little care need be used by the operator in locating the point of entry.

After the lance has been inserted and compressed air admitted, the peripheral surface of the lip 182 is subject to a squeezing pressure in the direction indicated by the arrows 186. This produces a self-sealing effect and greatly reduces the force required to maintain the lance in engagement with the bucket. It will be appreciated by one skilled in the art that the length of the lip 182 may be increased to enhance the gripping effect and to make it unnecessary for the operator to apply any force to maintain the lance in the inserted position.

In order that the diaphragm 180 may be readily replaced the socket 183 is connected to the line 164 by means of a threaded connection 187 or the like. Thus the socket may be quickly unscrewed and removed from the bucket and a replacement diaphragm substituted. The construction disclosed, while preventing the escape of compressed air, makes it unnecessary to use a lance coupling of a type employing a thread, bayonet or similar locking means; consequently, the lance may be instantly pulled clear without regard to the pressure being applied. While the above constitutes a preferred inlet construction it will be apparent that the invention in its broader aspects is not limited thereto.

The lance 140 preferably has a tip portion consisting of a length of pipe from two to four or more feet in length. This permits the operator to stand well clear of the bucket while it is discharging its load of concrete. in operation it is suificient for the operator to insert the air lance 140 into the air inlet device 135 and to operate the valve 141. The valve 142 is of the 3-way springreturned type internally so constructed that depressing the handle 143 thereon causes compressed air to flow from the line 141 into the line 164 in the bucket. Relieving pressure on the handle 143 first causes the line 141 to be shut off and then opens or vents the lance, and the air inlet which it engages, to the atmosphere. The latter takes place through a vent 144.

Having understood the construction of the inlet together with the air lance 140 and its associated valve, it will be helpful to outline a typical operating sequence. Initially the air inlets are both open to the atmosphere. Consequently the reservoir 134, isolated by the check valve 175, is connected by the valve 133 to apply pressure to the plunger end of the rams 50, 50a. This causes the gates to be held very forcefully in the closed position with a good seal at both the gasket 145 and the mating lips 147. It may be noted incidentally that even if the pressure in the reservoir should be dissipated as a result of leakage somewhere in the system there is no tendency for the gates to move to the open position. By way of additional precaution, however, the plunger 53 of the ram may be biased toward its retracted position by means of a coil spring 200 anchored at any convenient point. Such a spring has been shown in Fig. 2 but has not been included in the remainder of the figures to avoid complicating them.

With the gates in the closed position the bucket is filled at the mixer after which it is transported to the job by a railroad car or the like and lifted into the pouring position by means of a crane. With the bucket properly positioned for pouring, the operator, equipped with the portable air line 141, need merely insert the air lance 140 connected thereto into either one of the inlet devices 135, 136 whichever is more easily available. Since inlets are placed at diametrically opposite points on the bucket and since the socket 183 tolerates a considerable amount of angularity, rotation of the bucket is not necessary. Next the operator depresses the valve handle 143 causing admission of compressed air and moving the control valve 133 into the position disclosed in Fig. 6. This causes the ram plungers 53, 53a to move into their extended positions, and the linkage con nected thereto applies a powerful opening force to the gates. Simultaneously the reservoir 161 is recharged.

After the load of concrete has been fully or partially dis charged the operator may, at will, cause the gates to close merely by relieving his grip on the operating handle 143 of the control valve. The active air inlet, for example 135, will be immediately vented by the escape of air through the vent 144 causing the slide valve 133 to assume its alternative position and causing closure of the gates by the air stored in the reservoir 161. As an alternative to operating the valve 142 the gates may be closed merely by jerking the air lance out of the bucket.

The safety of such an arrangement will be readily appreciated by one familiar with conditions as they exist in the field. On large construction jobs the bucket is frequently suspended from a cableway several hundred feet in length. Such a cahleway forms a taut catenary in which extremely high tensile forces are developed in the cables due to the vertical loading which, in the present instance, may be in the neighborhood of fourteen tons. As the concrete is discharged and this force is relieved, it is a common occurrence for the bucket to spring into the air to a height of fourteen feet or more. Using conventional equipment this constitutes an extreme hazard to the personnel since the operator, with a grip on the bucket, may suddenly find himself jerked into the air.

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8 In a number of instances this type of accident has resulted in fatalities. By way of contrast upward spring of the bucket disclosed in the present invention merely causes the air inlet device or 136 as the case may be to be pulled away from the lance which remains in the hands of the operator. Any tendency for the lance to catch or bind at the air inlet is completely eliminated by the structure previously described. It will be seen therefore that the present construction actually utilizes an occurrence which was formerly dangerous as a safe means for producing automatic cutoff after the load has been discharged. The operator need merely maintain a firm grip on the lance.

The upward spring of the bucket upon discharge is not peculiar to cableways. Even where the bucket is suspended from a crane the length of the boom and the cable is generally suflicient to cause an upward spring of several feet. It will be seen, therefore, that regardless of what type of bucket suspension is used, any tendency for the bucket to move away from the desired position of discharge causes the air pressure to be reduced to atmospheric and the gates to be forced into the closed position. This is true whether the movement of the bucket is vertical or horizontal.

While it is true that the shape of the container described above tends to prevent arching of the concerete, nevertheless any concrete which does hang in the buckets will be trapped by the gates the instant the bucket leaves the dumping position and cannot drop out during return travel of the bucket. This removes one of the greatest hazards to personnel on a construction project. To insure that all of the concrete is discharged a conventional vibrator 188 may be attached to the conical portion of the bucket (see Figs. 3 and 6). This vibrator is connected to the bore 162 in the receiver by means of a vibrator supply line 189. Thus the vibrator will be put into operation automatically whenever pressure is applied to the bucket to open the gates. Tests have shown, however, that with the bucket shaped as described a vibrator is seldom required except when removing sticky concrete which has been transported a considerable distance. A cutoff valve [89a is provided to disable the vibrator under normal conditions.

I claim as my invention:

1. In a concrete bucket of the bottom dump type for use with a valve-controlled air line having a nozzle which may be supplied with compressed air with the valve in the open position and which is opened to the atmosphere when the valve is in its closed position, the combination comprising, a discharge gate movable between an open position and a closed position, a double-acting ram connected to said gate for moving the same between its respective positions, a compressed air inlet device at the wall of said bucket structure, means including a compressed air reservoir supplied by said inlet device for applying pressure to said ram, and valve means operated as an incident to the application of compressed air at said inlet device for moving said ram in the gate-opening direction and operated as an incident to the reduction of air pressure at said inlet device to cause said ram to move in a gate-closing direction, said inlet device being so constructed as to enable unimpeded insertion and retraction of the nozzle.

2. In a concerete bucket of the bottom dump type for use with a valve-controlled air line having a nozzle which may be supplied with compressed air with the valve in the open position and which is opened to the atmosphere when the valve is in its closed position, the combination comprising, a discharge gate movable between an open position and a closed position, a double-acting ram con nected to said gate for moving the same between its respective positions, a plurality of compressed air inlet devices accessible from the outside of said bucket, means including a compressed air reservoir supplied by said inlet devices for applying pressure to said ram, valve means operated as an incident to the application of compressed air at one of said inlet devices for moving said ram in the gate-opening direction and operated as an incident to the reduction of air pressure at said inlet devices to cause said ram to move in a gate-closing direction, and means for preventing leakage from the unused ones of said inlet devices.

3. In a concrete bucket arrangement, a portable air line having a valve at one end and provision for connection to a source of compressed air at the other, an extensive nozzle on said valve, said valve being arranged to supply said nozzle with compressed air when in the open position and to connect said nozzle to the atmosphere when in the closed position, a discharge gate movable between an open position and a closed position, a double-acting ram connected to said gate for moving the same between its respective positions, a compressed air inlet device, a compressed air reservoir, and valve means operated as an incident to the application of compressed air at said inlet device for connecting said ram to the inlet for movement in the gate-opening direction and operated as an incident to the reduction of air pressure at said inlet device to connect said ram to said reservoir for movement in the gate-closing direction, said inlet device being so arranged as to enable unimpeded insertion and retraction of the nozzle.

4. A bucket of the bottom dump type comprising a concrete container, a discharge throat at the lower end of the container, :1 pair of opposed clam gates for sealing oif said throat, said gates being pendulously pivoted for swinging movement about horizontal axes parallel to one another, a rocking member lying generally between said axes and pivoted at its center for rotation about an axis parallel to the axes of said gates, and thrust links pivotally connected between the ends of said rocking member and said gates, said rocking member and said links being so arranged that one of said links under condition of gateclosure occupies a position extending horizontally below the axis of said rocking member and the other link occupies a position in which it arches horizontally over the axis of said rocking member so that the mechanical advantage of said links relative to the rocking member is initially a maximum and progressively decreases as the gates swing from the closed to the open position.

5. A bucket of the bottom dump type comprising a concrete container, a discharge throat at the lower end of the container, a pair of opposed clam gates for sealing off said throat, said gates being pendulously pivoted for swinging movement about horizontal axes parallel to one another, a rocking member lying generally between said axes and pivoted at its center for rotation about an axis parallel to the axes of said gate-s, and thrust links pivotally connected between the ends of said rocking member and said gates, said rocking member and said links being so arranged that one of said links under condition of gate-closure occupies a position extending horizontally below the axis of said rocking member and the other link occupies a position in which it arches horizontally over the axis of said rocking member with the outer ends of each link connected to the associated gate at a point lying generally below the axis of swinging movement thereof so that the mechanical advantage of the rocking member on said gates is initially a maximum and progressively decreases as the gates swing from the closed to the open position.

6. A bucket of the bottom dump type comprising a concrete container having a discharge throat at the lower end thereof, a pair of opposed clam gates for sealing off said throat, said gates being pendulously pivoted for swinging movement about respective parallel horizontal axes, a rocking member pivoted medially of its ends for oscillation about a horizontal axis located generally in the vertical mid-plane extending between said axes of swinging movement of the gates, a thrust link pivotally connected to each gate at a point below the axis of swinging movement thereof and to an end of said rocking member respectively, one of said links extending over the axis of oscillation of the rocking member and the other link extending beneath said axis with the ends of said links in overlapping relationship and in close positions of proximity to and in parallelism with said rocking member when the gates are closed, said rocking member being adapted when moved in one direction of oscillation to impart opposite components of vertical movement to the ends of said links to which the rocking member is pivoted tending to misalign the links from their general positions of parallelism and also to impart opposite components of horizontal movement to said ends to swing said gates toward their open positions by a relatively great mechanical advantage which gradually decreases in proportion to the extent of misalignment of said links, and means for oscillating said rocking member to actuate said gates.

7. In a concrete bucket of the bottom dumping type. a gate for controlling the discharge of the concrete, double-acting ram means for operating said gate and having a pair of air connections for opening and closing said gate, source means for selectively providing compressed air, a reservoir of compressed air self-contained within the bucket structure, pressure responsive control means connected to said source means, and means operatively connected to said control means for applying clifi'erential air pressure between said air connections in one direction in response to an increase in pressure at said source means for opening said gate and for connecting said reservoir to one of said air connections in response to a decrease in pressure at said source means to apply dificrential air pressure between said air connections in the opposite directions for closing said gate.

8. In a concrete bucket of the bottom dumping type, a gate for controlling the discharge of the concrete, double-acting ram means for operating said gate and having first and second air connections for opening and closing said gate respectively, inlet means attachable to an external source of compressed air, means for connecting said inlet means to said first air connection for opening said gate in response to pressure in said inlet means, a reservoir of compressor air self-container within the bucket structure, means for recharging said reservoir from said inlet means in response to pressure therein, and pressure responsive control means connected to said inlet means for connecting said reservoir to said second air connection in response to a decrease in pres sure in said inlet means for closing said gate.

9. In a gate operating system for a movable closure, in combination, a fluid pressure receiver, a fluid cylinder, a piston in said cylinder positively connected to said closure, a movable valve normally connecting one end of said cylinder to said receiver and alternately connecting said one end of said cylinder to exhaust while sealing off said receiver, means for substantially simultaneously admitting fluid under pressure on occasion to said valve to move it to form said alternate connection and to the other end of said cylinder to move said closure in one direction and to said receiver to charge it with said fluid under pressure, means for connecting said first-named means to exhaust, and means for returning said valve to normal position when said first-named means is connected to exhaust whereby said fluid under pressure in said receiver enters said one end of said cylinder to move said closure in the other direction.

10. In a gate operating system, in combination, a penumatic storage tank, a pneumatic double-acting cylinder, a piston in said cylinder positively connected to a gate, a regulator having a valve therein, common means for admitting gas under pressure on occasion to one end of said cylinder to move said gate in one direction and to said regulator to move said valve to connect the other end of said cylinder to exhaust while sealing off said tank and to said tank to charge it wth said gas under pressure, and automatic means for returning said valve to 11 its original position when the admission of said gas under pressure to said common means is discontinued to open said common means to exhaust, said return of said valve connecting said other end of said cylinder to said tank to move said gate in the other direction.

11. In a gate operating system for a movable closure, in combination, a pneumatic pressure receiver, a doubleacting cylinder, a piston in said cylinder positively connected to said closure to move it, a pipe having, a coupling normally connected to exhaust, said coupling being adapted to be connected on occasion to a pneumatic pressure source closing said pipe to said exhaust, a pneumatic pressure receiver, a regulator having a valve therein, said receiver and said valve regulator and one end of said cylinder being in substantially direct communication with said pipe, a check valve connected between said pipe and said recever, the other end of said cylinder being normally in communicaton with said receiver through said valve regulator, means for maintaining said valve in said regulator in its normal position when said pipe is disconnected from said source, said valve regulator having an exhaust port in communication with said other end of said cylinder when said valve in said regulator is moved out of normal position upon connection of said coupling to said pneumatic pressure source, said movement of said valve in said regulator sealing ofl communication between said receiver and said other end of said cylinder.

12. in a device having a movable closure and a pressure fluid operating system therefor, in combination, a single pressure fluid admission member, an assembly having a cylinder and a relatively movable piston therein, said assembly being in positive connection to said closure to move it. a pressure fluid storage tank connected to said member and to one end of said cylinder, said cylinder having its other end connected to said member, a movable valve having one position opening said connection between said storage tank and said cylinder and another position to exhaust said one end of said cylinder when a pressure fluid source is applied to said member, said valve having a connection to said member to move said valve when said pressure fluid source is so applied, said connections to said member being in generally parallel flow arrangement, whereby upon such application of a pressure fluid source to said member, said cylinder and piston are relatively moved to move said closure, said valve is moved to its second mentioned position and said storage tank is charged with pressure fluid.

13. In a device having a movable closure and a pressure fluid operation system therefor, in combination, a single prissure fluid admission member, an assembly having a cylinder and a relatively movable piston therein, said assembly being in positive connection to said closure to move it, a pressure fluid storage tank connected between sztid member and one end of said cylinder, said cylinder having its other end connected to said member, a movable valve having one position opening said connection bctwcen said storage tank and said one end of said cylinder, means for normally maintaining said valve in said one position, said valve having a connection to said member to move said valve to another position shutting off said connection between said storage tank and said one end of said cylinder and opening said one end of said cylinder to exhaust when a pressure fluid source is applied to said member, said connections from said storage tank and said other end of said cylinder and said valve respectively to said member being in generally parallel flow arrangement. whereby upon such application of a pressure fluid source to said member said cylinder and piston are relatively moved to move said closure, said valve is moved to said another position, said storage tank is charged with pressure fluid, and, when said pressure fluid source is removed from said member, said valve is returned to its first mentioned position enabling said pressure fluid in said storage tank to relatively move 12 said cylinder and piston in a return direction to return said closure to its initial position.

14. In a device having a movable closure and a pressure fluid operation system therefor, in combination, a single pressure fluid admission member, an assembly having a cylinder and a relatively movable piston therein, said assembly being in positive connection to said closure to move it, a pressure fluid storage tank connected between said member and one end of said cylinder, a check valve in the connection between said storage tank and said member, said cylinder having its other end connected to said member, a movable valve having one position opening said oonnection between said storage tank and said one end of said cylinder while simultaneously shutting off said one end of said cylinder from exhaust, resilient means for normally maintaining said valve in said one position, said valve having a connection to said member to move said valve to another position shutting ofi said connection between said storage tank and said one end of said cylinder but opening said one end of said cylinder to exhaust when a pressure fluid source is applied to said member, said connections from said storage tank and said other end of said cylinder and said valve to said member being in generally parallel flow arrangement, whereby upon such application of a pressure fluid source to said member said cylinder and piston are relatively moved to move said closure, said valve is moved to said another position, said storage tank is charged with pressure fluid, and, when said pressure fluid source is removed from said member, said valve is automatically returned to its first mentioned position. enabling said pressure fluid in said storage tank to relatively move said cylinder and piston in a return direction to restore said closure to its initial position.

15. In a gate operating system having a plurality of gate closures, in combination, a pneumatic storage tank, a pneumatic double-acting cylinder, a piston in said cylinder connected to one of said gate closures, a link pivotally joining said closures and adapted to synchronize the respective movements thereof, a regulator having a valve therein, common means for admitting gas under pressure on occasion to one end of said cylinder to move said gate closures in one direction and to said regulator to move said valve to connect the other end of said cylinder to exhaust while sealing off said tank and to said tank to charge it with said gas under pressure, and automatic means for returning said valve to its original position when the admission of said gas under pressure to said common means is discontinued to open said means to exhaust, said return of said valve connecting said other end of said cylinder to said tank to move said gate closures in the other direction.

16. In a concrete bucket of the bottom dump type for use with a valve-controlled air line having a nozzle which may be supplied with compressed air with the valve in the open position and which is opened to the atmosphere when the valve is in its closed position, the combination comprising, a discharge gate movable between an open position and a closed position, a double-acting ram connected to said gate for moving the same between its respective positions, a compressed air inlet device at the wall of said bucket structure, a check valve, means including a compressed air reservoir directly supplied by said inlet device through said check valve for applying pressure to said ram, a valve means operated as an incident to the application of compressed air at said inlet device for moving said ram in the gate-opening direction and operated as an incident to the reduction of air pressure at said inlet device to cause said ram to move in a gate-closing direction, said inlet device being so constructed as to enable unimpeded insertion and retraction of the nozzle.

17. In a concrete bucket arrangement, a portable air line having a valve at one end and provision for connection to a source of compressed air at the other, an extensive nozzle on said valve, said valve being arranged to supply said nozzle with compressed air when in the open position and to connect said nozzle to the atmosphere when in the closed position, a discharge gate movable between an open position and a closed position, a doubleacting ram connected to said gate for moving the same between its respective positions, a compressed air inlet device, a check valve, a compressed air reservoir directly connected to said inlet device through said check valve and valve means operated as an incident to the application of compressed air at said inlet device for connecting said ram to the inlet for movement in the gate-opening direction and operated as an incident to the reduction of air pressure at said inlet device to connect said ram to said reservoir for movement in the gate-closing direction, said inlet device being so arranged as to enable unimpeded insertion and retraction of the nozzle.

18. In a concrete bucket of the bottom dumping type, a gate for controlling the discharge of the concrete, doubleacting ram means for operating said gate and having a pair of air connections for opening and closing said gate, source means for selectively providing compressed air, a check valve, a reservoir self-contained within the bucket structure and directly connectable to said source means through said check valve, pressure responsive control means connected to said source means, and means operatively connected to said control means for applying differential air pressure between said air connections in one direction in response to an increase in pressure at said source means for opening said gate and for connecting said reservoir to one of said air connections in response to a decrease in pressure at said source means to apply differential air pressure between said air connections in the opposite directions for closing said gate.

19. In a concrete bucket of the bottom dumping type, a gate for controlling the discharge of the concrete, doubleacting ram means for operating said gate and having first and second air connections for opening and closing said gate respectively, inlet means attachable to an external source of compressed air, means for connecting said inlet means to said first air connection for opening said gate in response to pressure in said inlet means, a reservoir of a compressed air self-contained within the bucket structure, a check valve, uncontrolled means for recharging said reservoir from said inlet means through said check valve in response to pressure therein, and pressure responsive control means connected to said inlet means for connecting said reservoir to said second air connection in response to a decrease in pressure in said inlet means for closing said gate.

20. In a concrete bucket of the bottom dumping type, a gate for controlling the discharge of the concrete and movable between fully open and fully closed positions; a double-acting air-actuated ram connected to said gate for moving the gate in the closing and opening directions respectively, said ram having gate-opening and gate-closing compressed air conections thereon; a compressed air inlet device; a storage reservoir having an air supply connection to said inlet device; and air line means connecting said ram to said reservoir and to said inlet device so that said ram may be supplied with compressed air therefrom, said means including an air-operated control valve for said ram having a control connection to said inlet device, said means being so constructed and arranged as to supply compressed air from said inlet device to the gate-opening compressed air connection on the ram when compressed air is supplied to the inlet device and to supply compressed air from said reservoir to the gate-closing compressed air connection on the ram when compressed air is no longer supplied to said inlet device.

21. In a concrete bucket of the bottom dumping type, a gate for controlling the discharge of the concrete and movable between open and closed positions; a doubleacting air-actuated ram connected to said gate and having gate-closing and gate-opening compressed air connections thereon for effecting ram movement in the closing and opening directions respectively; an inlet device connectable to an external source of compressed air; a storage reservoir; and means for connecting said inlet device to said reservoir and to said gate-opening air connection and for connecting said reservoir to said gate-closing connection, said means including an air-operated valve having a control connected to said inlet device, said valve being so constructed and arranged as to permit supply of compressed air to the gate-opening connection on the ram when compressed air is applied to said inlet device and to permit supply of compressed air from said reservoir to the gate-closing connection on the ram when compressed air is not applied at the inlet device.

22. In a concrete bucket of the bottom dumping type, a gate for controlling the discharge of the concrete and movable between open and closed positions; a doubleacting air-actuated ram connected to said gate for moving the gate in the closing and opening directions, said ram having gate-closing and gate-opening compressed air connections thereon for eifecting ram movement in the closing and opening directions respectively; an air inlet device connectable to an external source of compressed air; an air-operated control valve having a control line for controlling the same connected to said inlet device, said valve further having an air supply line connection to said inlet device including a check valve to prevent reverse flow; a reservoir connected to said air supply line between said check valve and said control valve; and air lines connecting said control valve to said ram compressed air connections, said control valve being so arranged as to supply compressed air from said air supply line to the gateopening connection on the ram when compressed air is applied to said inlet device and to supply compressed air from said reservoir to the gate-closing connection on the ram when compressed air is not applied to the inlet device.

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